


Domestic Sin

by Hella_Queer



Series: Delinquent AU [1]
Category: Free! Eternal Summer - Fandom
Genre: Anal Sex, Kinktober 2017, Lingerie, M/M, Over the underwear, Rimming, rin is thicc ok don't let kyoani art fool you, sourin
Language: English
Status: Completed
Published: 2017-10-29
Updated: 2017-10-29
Packaged: 2019-01-20 14:52:56
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,909
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/12435126
Author URL: https://archiveofourown.org/users/Hella_Queer/pseuds/Hella_Queer
Summary: Sousuke, still obediently covering his eyes, hears Rin walk to stand somewhere in front of him. A little tingle runs down his spine as the coat drops; a soft yet heavy whoosh that Rin kicks aside. Warm hands take his wrists, and Rin whispers:“Open.”





	Domestic Sin

**Author's Note:**

> Kinktober #9: Lingerie (Sourin)
> 
> Inspired by this drawing by @t_megumaru on twitter
> 
>    
>  [Here](https://twitter.com/t_megumaru/status/917810077259653120)

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When Sousuke returns home after his shift, he thinks he's been robbed. Or maybe pranked. The entire living room is rearranged; the couch is in the hallway leading to the bedroom, the floor is covered with small, circular rugs that he definitely didn't remember buying, in dark blue, maroon and black. There are tall lamps in both corners, ones he didn't have this morning, that have pink light bulbs that give the room an _atmosphere_. He's confused for all of thirty seconds, then remembers that he doesn't live alone anymore. 

“Rin!” 

“One sec!” 

When he started dating the little troublemaker, Mikoshiba said his biggest regret would be not arresting him while he had the chance. Now Sousuke knows that his biggest _mistake_ was letting Rin move in with him. He sighs and starts undressing, removing his belt and badge. He almost misses the days when he'd chase Rin down for some petty loitering. It was how they flirted back then. 

He hears footsteps approaching from down the hall, and turns just in time to see Rin climbing over the couch. Wearing a long, brown trench coat. 

“Do I even wanna ask?” Sousuke never thought he'd be dating someone he had to _keep up with_ , but Rin being seven years younger than him, with years of evading arrest and general mischief under his belt, it’s easy to feel resigned when he comes home to suspicious outfits and an interior makeover. Who knew thirty-one was the new ‘too old for this shit’. 

If Rin can sense his apprehension—which he can, there's no _if_ —he doesn't mention it. “You do. But it's a surprise.” He bounces up on his toes to kiss Sousuke’s jaw, perfectly at ease despite looking like a cliche drug dealer. “I didn't expect you home so soon,” he says, a little accusingly, ironically enough. “I’m not finished yet.” 

Sousuke takes another look around the room, wondering what the finished product is supposed to look like, if it isn't this. “With _you_ off the streets there's been less crime. Go figure.” He grins, easily sidestepping the kick to the back of his leg. “You won't get into the academy with those kinds of moves, kid.”

Rin tries his best to look offended, but the smirk pulling at the corner of his mouth gives him away. “Just go sit in the bedroom for like, ten minutes. Please?” He bats his eyelashes and juts out his bottom lip, managing to look both ridiculous and cute. Ridiculously cute. And incredibly cheesy. But Sousuke has learned what battles to pick, and this is one he leaves alone. 

“You're putting the couch back,” he says before kissing Rin’s cheek. He takes his things and climbs his way down the hall to his—theirs now—bedroom. He glances over his shoulder: Rin is already at work, moving the rugs with his feet as he decides where they look best. Sousuke shakes his head and disappears behind the door, thinking that he’ll use this time to change into more comfortable clothes. 

“And keep your uniform on!” 

Or not.

Ten minutes turns out to be twenty-five. An assortment of curses and crashes has Sousuke rising to his feet half a dozen times, and each time he's told to stay put. It's not that he doesn't trust the man, but this apartment is fairly new, and it's in a nice neighborhood, and he doesn't want to get kicked out due to noise complaints. Just when his nerves get the best of him, Rin announces that he's ready. Sousuke suddenly feels _not_ ready, but he opens up the door anyway. 

Aside from the couch now being in it's proper position, not much has changed. Perhaps the rugs are arranged differently? The lights could be pinker, maybe, or less pink instead? Sousuke proceeds into the empty room with caution, turning in a half circle, hands by his sides like he's got his gun with him. “Uhh, how much did you spend on all of this?” 

“Just sit down!” Ah, the bathroom, that's where Rin is. Sousuke relaxes just a little, still confused beyond belief. Rin hadn't texted him about any surprises while he was at work, when he usually would have. His boyfriend was an awful tease. He loved having all of Sousuke’s attention, so it was odd that he kept all of _this_ to himself. Sousuke hears the bathroom door open and turns his head in that direction, eagerly awaiting whatever Rin has in store for him. 

His boyfriend is still wearing the trenchcoat, but he's added makeup to the bizarre outfit. His eyes are sharp and warm, peeling away Sousuke’s clothes without laying a finger on him. The difference in their personalities couldn't be more prominent, because Sousuke strides forward with the intent to unwrap this little mystery with his own two hands. Rin, eyes twinkling with mirth, steps back accordingly. 

“I'm starting to think–”

“Don't think,” Rin interrupts. “Sit.” He nods to the couch, so Sousuke sits right in the middle, legs spread wide as he plants his elbows on his knees. He puts his chin in his hands and watches Rin with an amused expression, lips quirked in a little smirk. He's long since stopped being phased by such spontaneous things. Being with Rin came with a lot of surprises in general, so he had a lot of practice with keeping a poker face. 

Rin pulls a remote from one of the pockets—where did he even get this coat?—and music starts to pour in from the Bluetooth speaker on the kitchen counter. Sousuke recognizes it as the song he first saw Rin dance to, the one he deemed as him trying too hard. A fond smile softens his face, and Rin kisses him quick before moving behind the couch. Sousuke doesn't look, figuring this is part of the unveiling, too. 

“Sooooo,” Rin says from behind him, his voice catching on a grin. “I was at my storage unit the other day, and I found something of mine that I think you'll like.” 

_Storage unit, huh?_ That explained the new rugs and lamps. Rin was a hoarder, and had a bad habit of keeping things he probably shouldn’t. For the first few months of living together, an inflatable donut had hung on the wall behind the couch. It now hangs, deflated, in the hall closet, instead of in the trash, because along with being unable to tie a knot in a cherry stem—something Rin has endlessly mocked him for—he also can’t say no to his boyfriend.

“Oh, yeah?”’ Sousuke makes a show of covering his eyes with his hands and turning his head in all directions. “Is it an inflatable dragon? Cause I wouldn’t mind hanging that up.” 

Rin shoves him forward and Sousuke laughs. “No, you _ass_. God you’re the worst.” But he’s laughing too. 

Sousuke, still obediently covering his eyes, hears Rin walk to stand somewhere in front of him. A little tingle runs down his spine as the coat drops; a soft yet heavy _whoosh_ that Rin kicks aside. Warm hands take his wrists, and Rin whispers: 

“Open.” 

His hands are taken away before he can do it himself, and then Rin backs up. He twirls in a little circle, and stands with his hip cocked to the side as his final pose. That sharp smile comes into play the longer Sousuke sits in silence, and unlike most people when faced with speechlessness, Rin’s confidence only grows. 

Calling it a costume would be a lie. It’s strips of black fabric crudely imitating a costume, but even that isn’t the whole of it. 

Rin’s wearing some kind of harness-bra looking thing, with little bat wings in between his shoulder blades. Other than that his torso is bare, and his chest might as well be bare too. Sousuke can see his nipples under the little suspender-like straps. And the bottom half..

It’s a thong. It’s a thong with a tiny _tiny_ skirt that barely covers the swell of his ass. 

“Surprised?” Rin plucks at the waistband and lets it snap back against him. “Me too. I was afraid it wouldn’t fit anymore!” 

Sousuke still hasn’t spoken. He isn’t certain he can anymore. He’s seen Rin naked before, has seen him many times on and off stage in skimpy, revealing outfits. But something about this outfit, if it can even be called that, has his blood pumping a little faster. 

A bit put out now with his lack of reaction, Rin stamps his foot on the ground, the sound muffled by a dark blue carpet circle. “Fine. If you hate it _that much_ , I’ll take it off.” 

An open palm comes down on him, slapping his firm thigh hard enough to sting. 

“Ah!” Rin rubs at the slight pain, but there’s a fire in his eyes now. It wasn’t often that his boyfriend displayed his strength without being asked. And Rin likes things a little rough sometimes. “Fucking brute.” 

“What the hell is this?” Sousuke rasps, letting every ounce of arousal coat his voice. Rin takes to it immediately. 

“My old uniform. One of them at least.” He leans over Sousuke, hands on the back of the couch, chest in his face like he’s got something to shake at him. Sousuke nips at his collarbone, and slides his hands up his chest. “The club got _huge_ turnouts for Halloween.” Red eyes gleam at him from behind Rin’s messy-on-purpose bangs. “I was a crowd favorite.” 

Sousuke doesn’t need to imagine what those nights were like, because his reality is much better. “I’ll bet.” He kisses his neck before taking his hands away. “Bend over.” 

Rin does as he’s told, though with a little flair. He turns around and spreads his legs wide, swivels his hips in tight circles as he slides his hands down his body, until they’re braced against the floor. That little strap of the thong shouldn’t be able to hold him, but it does, leaving not much to the imagination. 

Sousuke grabs a handful of Rin’s ass and squeezes, moving closer to the edge of his seat. He was never one for flashy acts of seduction, but seeing his boyfriend on display like this was probably his favorite. What was that saying? ‘Thick thighs save lives’? Well if that was true, Rin has saved his life ten times over. 

He spreads his cheeks apart and tongues at where the thong covers his hole. Rin gasps and wobbles, and Sousuke smirks against him. He goes lower, mouthing at his balls while he marks his thighs with possessive fingers. He’s slow and sloppy with it, fingers kneading his ass as he wets the stretchy fabric. The more Rin struggles to keep his pose, to not push back against him, the more Sousuke gives, until the damn thing may as well be transparent. 

“Lube?” He asks once he’s had his fill. His fingers replace his mouth, cupping Rin and letting him grind onto his hand. 

Rin looks up at him from between his legs, his face a pretty pink. “And here I thought you were playing hard to get.” He tries for coy, but that doesn’t really work when he’s shaking and on the verge of falling over. Sousuke grants him mercy and stands him back up, slowly so he won’t get dizzy, before pulling him down to his lap. 

“Why would I need to do that?” Sousuke kisses Rin’s neck, more teeth than lips, more biting than sucking. “I’ve already got you.” His lips travel up his jaw, to his ear, across his cheek. “So now I’m going to have you.” 

No matter how experimental Rin likes to be, nothing about the way he comes undone changes. Yet Sousuke feels like it’s their first time every time, no matter how sappy that is. Perhaps that part of Rin has rubbed off on him, instead of his rebellion that Sousuke denies he ever lost in the first place. Whatever the case, nothing is ever boring between them, especially not tonight. 

Rin tastes like their first kiss, too, hot lips fighting with his, wanting control just to say he got it. Sousuke gives it to him willingly, parts his lips and relaxes his jaw and lets Rin lick inside like he doesn’t have the power to flip him onto his back and swallow him whole. They both know he can, but the fact that he doesn’t is what has Rin pawing at the buttons of his shirt. (The one he told Sousuke not to take off, but whatever). 

“Lube,” Sousuke says again, a demand instead of a question. His shirt is behind the couch, and his pants are open and pulled down just far enough to free his length. 

Rin rises up on his knees and guides his hand under the thong, back to where his mouth had been, and the fabric isn’t the only thing that’s wet. 

“Don’t need it,” he says in a smug, breathy whispers as Sousuke works a finger inside. 

Rin never stretched himself enough. Not because he was reckless, but because two of his fingers were the same as one of Sousuke’s, plus a little bit more. So whenever he was left to the task of getting himself ready, and was too impatient to get up to three—

 _”Fuck.”_

He’s hot and tight and _tight_ , just shy of uncomfortable as he bottoms out on Sousuke’s lap. They regard each other with lidded eyes, hands clutching hips and shoulders as they get adjusted. Rin can’t decide if he wants to smile impishly or pout with every shift of Sousuke’s body. The muscles in his thighs jump as he moves forward and drapes his arms around Sousuke’s shoulders. 

“Don’t hold back.” A plea that rides a broken moan. Gone is the coy dancer and the mischievous delinquent. Rin is all that’s left, and he’s both of those things and also neither, sitting on his dick with soft lips coaxing his open so they can breathe in the same gasping breaths. 

Sousuke’s work calloused hands grip Rin’s thighs as he urges him up, and eases him back down. With how tight he is, Rin can’t move too fast, but Sousuke is deep and fills him up just how he likes. They rock together, Rin’s thong pulled to the side, stretched far so that his cock can rub up against Sousuke’s stomach as he grinds down in his lap. 

“I can see why this was a crowd favorite,” Sousuke murmurs as he tucks Rin in close. “If only they could see you now, see that you’re _mine_.” 

It wasn’t often that Sousuke got possessive. But imagining the crowd of hungry eyes, all those men lusting after his boyfriend, even back then, made him hold him a little tighter. Rin cries out when Sousuke hits that perfect spot inside of him, and stays there, insistent and merciless. Sousuke strokes him quick, a great contrast to the slow rolls of his hips, and Rin bites down on his shoulder when he’s close. 

“You’d let me, wouldn’t you?” Sousuke sucks on Rin’s lip, bites it sore just to soothe it again. “Let me show you off to all those people who thought they could have you?”

Rin whines, even as he thumps his fist against his chest. His boyfriend was a double edged sword; he wanted Sousuke to act a certain way, but not when he was incapable of playing along. Not when his hips had a mind of their own and couldn’t help but to twitch and shake when Sousuke smacks his ass again. Not when his voice is lost under the glow of the pink lights, when it highlights his flushed cheeks and hardened nipples. 

Rin comes with both of hands buried in Sousuke’s hair, his back arching as he makes a mess of Sousuke’s hand. Sousuke doesn’t hold back, as promised, and fucks up into him as he wrings him dry, until he fills Rin up even more as he drops off the edge himself. Rin holds onto him, spent and satisfied, and Sousuke doesn’t complain about the mess, comfortable for now. 

“Was any of this… _setting_ necessary?”

Rin huffs a laugh into his chest. “Nah. I had all this stuff in my storage unit, and they were gonna charge if I didn’t empty it out today.” 

That explanation makes the most sense out of everything that’s happened tonight, but Sousuke can’t say he didn’t like the outfit. 

“Why did you have all this stuff, anyway?” Even though a dozen random rugs and oddly shaped lamps weren’t the weirdest things that Rin has brought to his apartment. 

“Dunno.” Rin makes a face as Sousuke’s softened cock slips out of him. “But I kinda like the rugs. Can we keep them?”

Sousuke closes his eyes, already resigning his future self to a neck cramp. The couch is too comfortable in his post orgasmic state, and he wants to stay this loose for as long as he can. “I suppose.” 

Rin hums, and presses a kiss to his chin. “And the light bulbs, too.” 

“No.”

 _”Please?”_

“We don’t need pink lightbulbs.” 

“We don’t need strawberry lube either but we have it!” 

If Sousuke gives in to his boyfriend—which he will, there’s no _if_ —it’ll be with a reluctant sigh and an exaggerated eye roll. Which in turn will be rewarded with a kiss, and his favorite smile. So really, he comes out breaking even.


End file.
